Phylogeny Of Pinus Henryi And Its Relative Species Based On Multiple DNA Sequences

Pinus henryi Mast.,an endemic pine in China,mainly distributes over Daba mountains,Wushan mountains and offshoots of YunGui plateau.Most forest of P.henryi has been destroyed by man and this species is listed as rare plant.P.henryi is often regarded as taxonomic variant species of P.tabuliformis or P.massoniana.Several experts argued that it should be independent species based on the differences of timber anatomy and chemical components.According to geographic distribution,P.henryi is linked together with P.tabuliformis in north,neighbors with P.hwangshanensis in east,crisscrosses with P.yunnanensis in south,and overlaps with P.massoniana(lower at altitude).Complicated relationships exist in P.henryi and its relative species due to similar morphic characteristics,overlapped distribution and extended hybridization in pines.Considered that less information would be supplied by single DNA fragment,the phylogeny and evolutionary history of P.henryi and it relative species were explored using twelve DNA fragments from chloroplast(matK, rbcL,rpl20-rps18,trnV,rpoC2-rps2,psaB-prs14 and rrnS-trnN),mitochondrial (nad1,nad5,matR,ssu rRNA)and nuclear genomes(ifg1934).The results indicated that:Firstly,according to the different charactistics compared with it relative species,P.henryi should be regarded as a seperate species rather than taxonomic variant species of P.tabuliformis or P.massoniana.Secondly, P.henryi as an independent species is close to P.hwangshanensis,P.tabuliformis and P.yunnanensis and far from P.massoniana,P.tabuliformis and P.yunnanensis have closer relationships than the others.Thirdly,using molecular dating approaches,we estimated that P.massoniana origined foremost at Oligocene epoch about 28 million years ago(MYA),and it owns more archaic genetic components because of its slow evolutionary rate;P.henryi and P.hwangshanensis diverged later at Miocene epoch about 9.7MYA and 6.9MYA relatively;and a divergence time of Pliocene epoch 3.4MYA is obtained for P.tabuliformis and P.yunnanensis.Late divergent time and frequent gene flow might contribute to phenomena of the shared genomes in P.henryi and it relatives.